|The role of SLIT-ROBO signaling in proliferative diabetic retinopathy and retinal pigment epithelial cells. |
Weiyan Zhou,Wenzhen Yu,Wankun Xie,Lvzhen Huang,Yongsheng Xu,Xiaoxin Li
SLIT-ROBO signaling acts as a cue in neuronal guidance and plays a role in vasculogenesis and angiogenesis. The aim of this study is to explore the effects of robo1 and slit2 on the formation of fibrovascular membranes (FVMs) in samples from patients with proliferative diabetic retinopathy. The effects of advanced glycation end products (AGEs) on robo1 and slit2 expression in human retinal pigment epithelium (RPE) cells and the role of recombinant N-SLIT2 protein in human RPE cell regulation were investigated.Full Text Article
|Slit-2 repels the migration of olfactory ensheathing cells by triggering Ca2+-dependent cofilin activation and RhoA inhibition. |
Huang, ZH; Wang, Y; Su, ZD; Geng, JG; Chen, YZ; Yuan, XB; He, C
Journal of cell science
Olfactory ensheathing cells (OECs) migrate from the olfactory epithelium towards the olfactory bulb during development. However, the guidance mechanism for OEC migration remains a mystery. Here we show that migrating OECs expressed the receptor of the repulsive guidance factor Slit-2. A gradient of Slit-2 in front of cultured OECs first caused the collapse of the leading front, then the reversal of cell migration. These Slit-2 effects depended on the Ca(2+) release from internal stores through inositol (1,4,5)-triphosphate receptor channels. Interestingly, in response to Slit-2 stimulation, collapse of the leading front required the activation of the F-actin severing protein cofilin in a Ca(2+)-dependent manner, whereas the subsequent reversal of the soma migration depended on the reversal of RhoA activity across the cell. Finally, the Slit-2-induced repulsion of cell migration was fully mimicked by co-application of inhibitors of F-actin polymerization and RhoA kinase. Our findings revealed Slit-2 as a repulsive guidance factor for OEC migration and an unexpected link between Ca(2+) and cofilin signaling during Slit-2-triggered repulsion.
|Dual trafficking of Slit3 to mitochondria and cell surface demonstrates novel localization for Slit protein. |
Little, M H, et al.
Am. J. Physiol., Cell Physiol., 281: C486-95 (2001)
Drosophila slit is a secreted protein involved in midline patterning. Three vertebrate orthologs of the fly slit gene, Slit1, 2, and 3, have been isolated. Each displays overlapping, but distinct, patterns of expression in the developing vertebrate central nervous system, implying conservation of function. However, vertebrate Slit genes are also expressed in nonneuronal tissues where their cellular locations and functions are unknown. In this study, we characterized the cellular distribution and processing of mammalian Slit3 gene product, the least evolutionarily conserved of the vertebrate Slit genes, in kidney epithelial cells, using both cellular fractionation and immunolabeling. Slit3, but not Slit2, was predominantly localized within the mitochondria. This localization was confirmed using immunoelectron microscopy in cell lines and in mouse kidney proximal tubule cells. In confluent epithelial monolayers, Slit3 was also transported to the cell surface. However, we found no evidence of Slit3 proteolytic processing similar to that seen for Slit2. We demonstrated that Slit3 contains an NH(2)-terminal mitochondrial localization signal that can direct a reporter green fluorescent protein to the mitochondria. The equivalent region from Slit1 cannot elicit mitochondrial targeting. We conclude that Slit3 protein is targeted to and localized at two distinct sites within epithelial cells: the mitochondria, and then, in more confluent cells, the cell surface. Targeting to both locations is driven by specific NH(2)-terminal sequences. This is the first examination of Slit protein localization in nonneuronal cells, and this study implies that Slit3 has potentially unique functions not shared by other Slit proteins.